Study on the deflagration reaction process of oil gas in long-narrow confined space based on PLIF and flame spectra

Oil gas explosion in long-narrow confined space is a typical unsteady combustion process. To study the reaction process, two experiment techniques are adopted in this research. One is planner laser induced fluorescence, which is used to achieve the transient measurement of free radicals in unsteady premixed combustion field. The other one is the spectral testing technique, which is used to measure the luminescence spectrum characteristics of oil gas combustion flame. The distribution of OH radical and CH radical at different positions in the combustion field, the common partition of deflagration flame structure under different oil gas concentrations, and the main luminescence spectra of radicals such as OH, CH, C₂, C₃, CO₂, H₂O and HCO are obtained. By comparing the above three aspects, the combustion reaction process of premixed mixture is revealed, driven by the coupling effect of chemical reaction and fluid flow in the process of explosion propagation. The process can be described briefly as follows. In the “outer flame zone”, large hydrocarbon molecules are mainly transformed to small molecules and free radicals by means of pyrolysis, dehydrogenation and oxidation. In the “inner flame zone”, carbon particles and combustion products produced and gathered after relevant reactions.